大豆疫霉菌中国分离物的来源及外来小种风险研究

Phytophthora sojae is one of the most destructive pathogens of soybean. It is soilborne and host-specific. Under saturated soil conditions, P.sojae can infect soybean plants throughout the growing season to cause seriously damages. Up to now, P. sojae has occurred at many soybean-growing regions, and causes heavy loss in some major soybean production countries such as USA, Canada and Argentine. To prohibit P. sojae from invading our country, it has been listed in quarantine important plant pathogens since 1986. However, P. sojae was discovered in Heilongjiang , Jilin and Beijing in China in 1989. Since then, the Phytophthora root rot of soybean has been becoming important problem impairing soybean production in Heilongjiang province. Soybean has been cultivated in China for a long history, but the Phytophthora root rot was a new disease of soybean in China. Where did the pathogen come? Because P. sojae has been detected in soybean seeds or soils carried by soybeans imported from other countries, it is possible that P. sojae occurring in China was exotic. However, soybean originated in China, based on the theory of coevolution of plant pathogen and host, P. sojae should originate in China. Lohnes et al. (1996) identified resistance to several races of P. sojae in soybean germplasm from China, they found that the resistance to P. sojae existed in many accessions from Yellow River and Huaihe River Basins in China, so they suggested that P. sojae had a long evolution history and genetic diversity in China. In view of the fact that P. sojae occurred in China and some people queried the necessity of quarantining for P. sojae, it is necessary to understand the origin of P. sojae in China and to assess the risk of exotic isolates of P. sojae. The plant pathogen and host are coevolationary in a pathosystem. The most abundant genetic diversity of a pathogen and its host commonly exists in the center of origin of the host. If P. sojae originated in China, it should have abundant genetic and virulent diversity and the soybean should have abundant resistant diversity to P. sojae in China. Therefore, we surveyed the distribution of P. sojae in China, studied the genetic and virulent diversity of P. sojae and resistant diversity of soybean germplasm in northeastern regions and Yellow River and Huaihe River Basins in China, and evaluated resistance to races of P. sojae from USA in cultivated soybean cultivars and breeding lines in the two regions, and investigated genetic relationship between Chinese isolates of P. sojae and American isolates of P. sojae. The following were the main results: (1) P. sojae was discovered in Yangtze River Basin, Yellow River and Huaihe River Basins in China; (2) There are abundant genetic and virulent diversity of P. sojae in China, and there are different virulence constitution of P. sojae among different regions. (3) There is genetic difference between tested Chinese isolates and American isolates of P. sojae by RAPD analysis; (4) Resistance soybean germplasm to P. sojae are abundant in China. These results will be useful for risk assessment of P. sojae, screening resistance soybean germplasm and breeding resistance soybean cultivars and. Also, these results will provide scientific basis for formulating a policy of quarantine and measurers controlling Phytophthora root rot of soybean.

利用分子标记技术和常规方法研究我国大豆疫霉菌遗传及毒力多样性、中国和美国大豆疫霉菌的遗传关系，研究大豆抗性多样性及黄淮和东北主栽大豆品种对重要美国小种的抗性，探讨我国大豆疫霉菌的可能来源、变异和进化途径，分析外来小种造成危害的可能性。研究结果将为大豆疫霉菌危险性评价提供重要指标，为检疫和防治策略的正确制订提供重要依据。